package com.srcptit.java.training.kienbd.btvn1;
import java.util.Scanner;
public class Muc1Bai5FIBOLNACCI{
        static void Fibolnacci(int n){
                int a = 0;
                int b = 1;
                int dem = 2;
                int next = 0;
                while(dem<n) {
                    next = a + b;
                    dem++;
                    a = b;
                    b = next;    
                }
                System.out.println(next);
        }
	public static void main(String args[]){
            Scanner input = new Scanner(System.in);
            String str = input.next();
            try {
                int n = Integer.parseInt(str);
                System.out.println("YES! So Fibolnaaci thu "+n+" : "); 
                Fibolnacci(n);
            }catch(Exception e) {
                System.out.println("NO! Vui long nhap lai.");
            }
            input.close();
	}
}